1. Field of the Invention
This invention relates to an amplifier circuit.
2. Background Art
Low-noise radio-frequency amplifiers constituting mobile electronic devices require small size, low noise, and mass productivity. Integration of amplifier circuits including radio-frequency transistors on a silicon substrate facilitates ensuring mass productivity while maintaining low noise figure (NF) in the radio-frequency band.
Here, the radio-frequency characteristics depend primarily on the characteristics of the radio-frequency transistor. However, the radio-frequency transistor is incorporated in the amplifier circuit, and separately measuring its characteristics requires providing measuring terminals. However, such measuring terminals increase chip size and decrease mass productivity.
JP-A-9-283576 (1997) (Kokai) discloses a technique related to a semiconductor device that allows dark current measurement in the chip state. In this technique, a probe test electrode is connected to the base electrode of a transistor. A probe is brought into contact with the base electrode to measure DC current amplification factor (hFE). Then, a forward current is passed between the collector and the emitter to blow the interconnected portion between the base electrode and the probe test electrode, and the collector-emitter dark current is measured.
However, even using this technique, the DC current amplification factor of a transistor incorporated in an amplifier circuit is difficult to measure, and the amplification characteristics need to be directly measured in the delivery inspection of products.